Potential Incompatibilities
Erlang 5.0/OTP R7B

This document contains a list of all potential incompatibilities between Erlang 5.0/OTP R7B and the previous version Erlang 4.9/OTP R6B, and is an extract from the release notes for the respective applications.

Appmon-2.0.1

• All Appmon modules are listed in appmon.app.
  Own Id: OTP-3543
  Aux Id: Seq 4487
• The main window is now similar to that of the other tools, showing only one node at a time.
  Own Id: OTP-3541
  Aux Id: OTP-1609, OTP-3487, OTP-3609

Erl_Interface-3.2.3

• The reference type has been extended from 18 bits to 82 bits. For compatibility with older nodes, an R6 node can send a ref to an older node; if the older node sends it back, it has lost all but its 18 least significant bits, but still compares equal to the original ref.
  The external format has been extended to represent the new longer refs; that means for example that binaries with refs, produced on an R6 node, cannot be converted to a term on an older node.
  In erl_interface, a function erl_mk_long_ref has been added, and macros ERL_REF_NUMBERS and ERL_REF_LEN.
  Own Id: OTP-3140
  Aux Id: OTP-3139

ERTS-5.0.1

• The maximum number of ports that can be opened using erlang:open_port/2 can now be configured using the environment variable ERL_MAX_PORTS.
  By default, the maximum number of ports is 1024.
  Note that the default value of 1024 in rare cases may be lower than the default value in previous releases (it used to be the maximum number of file descriptors for the current process on Unix).
  Own Id: OTP-3494

Kernel-2.6.1

• On Unix, os:cmd/1 previously used a dedicated subprocess, which meant that calls to os:cmd/1 were serialized. This is no longer the case.
  (For R7A users: the solution in R7A was too simple; compatibility with earlier releases has been restored.)
  The kernel configuration parameter start_os has been removed.
  Own Id: OTP-3466
  Aux Id: seq4333
• When supplying option {packet,PacketType} to gen_udp:open(Portnum,Options) it now exits with badarg. In previous releases this option was silently ignored, which was too forgiving since UDP datagrams are packets by definition, and hence this option was obsolete. Furthermore, the more exotic PacketType values, e.g. asn1, cdr, sunrm, fcgi, has never been implemented for UDP.
  Programs that supply this obsolete option to gen_udp:open/2 will probably crash when running on this release.
  Own Id: OTP-3690
• The disk_log module has been improved as regards distribution. The value returned from open/1 when opening a distributed log has been modified. The modification is incompatible with the previously returned value. Attempts to open a distributed log on a node running new code from a node running old code, and vice versa, results in a nodedown error message.
  info/1 returns two more tags, node and distributed.
  The new function lclose/1 closes a log on the current node.
  The layout of the continuation returned from chunk{_step} has been changed, and the new function chunk_info/1 returns the node where chunks are read from.
  The new function accessible_logs/0 returns the names of disk logs accessible on the current node.
  Own Id: OTP-3531
  Aux Id: Seq 4426, Seq 4258

Mnesia-3.9.2

• The major version number change implies that Mnesia-3.9 and later will not be able to talk with other Mnesia nodes which are running Mnesia-3.7.*.

Orber-3.1.8

• To be able to start Orber as lightweight, the Mnesia application has had to be removed from the application dependency list in the orber.app file. If Orber is not started as lightweight, it can therefore be necessary to explicitly add mnesia to this list.
  For example, you cannot upgrade an older version of Orber (not started as lightweight) to this version without adding mnesia to the list.
• The function corba_object:non_existent/1 have been updated to follow the CORBA 2.3 standard. Hence, Intra-ORB communication with ORB:s not supporting this standard will fail.
  The operation corba_object:not_existent/1 allows users to use the old standard. Consult the ORB vendor's documentation to decide which function to use.
  Own Id: OTP-3679
• When using the IC option, ic:gen(IdlFile,[{timeout,"module::interface"}]), an EXIT was the timeout result. Now, the system exception COMM_FAILURE is raised.
• The change in InitialReferences.idl to clash with the CORBA standard implies changes in the code that use this interface. See the OTP-3468 and OTP-3155 in the "Fixed bugs and malfunctions" chapter in the release notes for Orber-3.1.2.

SNMP-3.2.1

• When importing MIBs, it must be ensured that the imported MIBs as well as the importing MIB are compiled using the same version of the SNMP-compiler.

STDLIB-1.9.1

• The sets and dict modules have been updated. There are now the following modules: dict (unordered dictionary), orddict (ordered dictionary), sets (unordered set), and ordsets (ordered set).
  The API functions have been extended to allow more efficient updates of sets and dictionaries. Some API functions are now considered deprecated. See the documentation for each module.

  Note that dict module uses a new internal representation. Applications that bypassed the documented API functions and assumed that dictionaries were lists will no longer work.
  Own Id: OTP-3519